D drive becomes a file?

This is my first post and unfortunately, to me, it is a troubling one. Hopefully, some of us here are able to help me in this.

I have discovered that my comp. has gotten Trojan virus in the C drive. Have run a antivirus software on it, managed to delete and quarantine 3 threats. Unsure what to do with it. Meanwhile, when I tried to open my D drive, I encountered this message of no permission to access the drive. Suspected it may got the virus too. I have done a anti virus software check on it. And it deleted one threat.

When i tried to access my D drive again, i have this message " to open file D:/, select any of this programs to open it, words, excel etc etc"...
I was stunned. My D drive has become a D file?

In this case, what should I do to revert it to original status?Help!:dead: